/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.rpc;

import org.apache.thrift.TConfiguration;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TTransportException;

public class AutoScalingBufferReadTransport extends NonOpenTransport {

    private final AutoResizingBuffer buf;
    private int pos = 0;
    private int limit = 0;

    public AutoScalingBufferReadTransport(int initialCapacity) {
        this.buf = new AutoResizingBuffer(initialCapacity);
    }

    public void fill(TTransport inTrans, int length) throws TTransportException {
        buf.resizeIfNecessary(length);
        inTrans.readAll(buf.array(), 0, length);
        pos = 0;
        limit = length;
    }

    @Override
    public final int read(byte[] target, int off, int len) {
        int amtToRead = Math.min(len, getBytesRemainingInBuffer());
        System.arraycopy(buf.array(), pos, target, off, amtToRead);
        consumeBuffer(amtToRead);
        return amtToRead;
    }

    @Override
    public void write(byte[] buf, int off, int len) {
        throw new UnsupportedOperationException();
    }

    @Override
    public final void consumeBuffer(int len) {
        pos += len;
    }

    @Override
    public TConfiguration getConfiguration() {
        // should never call this method.
        return null;
    }

    @Override
    public void updateKnownMessageSize(long size) throws TTransportException {
    }

    @Override
    public void checkReadBytesAvailable(long numBytes) throws TTransportException {
    }

    @Override
    public final byte[] getBuffer() {
        return buf.array();
    }

    @Override
    public final int getBufferPosition() {
        return pos;
    }

    @Override
    public final int getBytesRemainingInBuffer() {
        return limit - pos;
    }

    public void resizeIfNecessary(int size) {
        buf.resizeIfNecessary(size);
    }

    public void limit(int newLimit) {
        this.limit = newLimit;
    }

    public void position(int newPosition) {
        this.pos = newPosition;
    }
}
